You can remove old grease stains with dish soap.
Yes, it's that easy. I found this out when I went to the cleaners and they were not able to remove a stain via dry cleaning. They were afraid of ruining the material if they kept trying, but they said that if I wanted to try it, I could give it a shot with dish soap. With the stain the shirt was useless, so I figured I didn't have anything to lose. I applied Dawn—yes, the one with the little yellow duckling—directly on the stain, and pressed on it with another edge of the shirt so the textile would absorb the soap well. I let it sit for 3 minutes, and placed it in the washer on delicate cycle.
It worked like a charm. The shirt is now stain-free, it didn't hurt my wallet, and I learned something new. Definitely a win-win.